The present invention relates to a coupling piece with damping function for simultaneous earth and/or rock drilling with an upper rotary percussion device and a lower percussion device.
In a previously known drilling device, see U.S. Pat. No. 5,355,966, for simultaneous drilling with an upper rotary percussion device and a lower percussion device the feed force on the drill tube string and on the lower percussion device is achieved through displacement of the upper rotary percussion device towards the ground. A drawback with this solution is that drilling cannot occur optimally since one cannot control the feed force on the upper rotary percussion device and on the lower percussion device independent of each other for adaption of the drilling to local variations in the ground conditions.